The U.S. military has begun the reversal of a controversial 16-year-old law that bans openly gay men and women from serving in its ranks.

At a hearing in Washington, D.C., on Tuesday morning, U.S. Defence Secretary Robert Gates tapped his chief legal adviser and a four-star army general to lead a landmark study on how the military would lift its ban, known commonly as "Don't Ask, Don't Tell."

One man's story

David Hall, 29, was discharged from the U.S. Air Force in 2002 because he is gay. He was discharged under the controversial "Don't Ask, Don't Tell" law, which makes it illegal for openly gay people to serve in the military.

Hall is now director of development for the Servicemembers Legal Defence Network (SLDN), an organization set up to fight the law, which went into effect in 1993. Since then, 14,000 people have been discharged from the U.S. military for being gay, according to SLDN. On the eve of congressional hearings into the future of the "Don't Ask, Don't Tell" law, CBC News producer Carla Turner spoke with Hall about his experience with the law.

How were you discharged?

I was enlisted in the air force for five years, following the footsteps of dad and stepdad who both served 20 years in the air force.

At the five-year point I went back to school to become an officer. So I was a cadet in the Reserve Officer Training Corps (ROTC).

After one year of being cadet in ROTC, a fellow cadet went to the commander and said that I was gay and that my boyfriend at the time, who was also a cadet, was gay. After an investigation, I said nothing. I just didn't say anything. A few months later they said that I would be discharged for homosexual conduct based on what this one person had said.

What was that like?

It was disheartening. I was ranked number one in my class. I had just received my pilot slot. That was one of my dreams to fly planes. After loading bombs and missiles on planes for five years, I was looking forward to actually flying them. It was very disappointing to know that the only reason I couldn't become a pilot was because I was gay. It had nothing to do with how well I did while I was in the air force or as a cadet.

You were discharged based on a comment by one person?

They call it a "Don't Ask Don't Tell," but what they really mean is don't tell anyone, ever. So this person knew that we were gay and that they were dating, so they take that as, well, this person knew, so you told somebody.

You must be angry?

A lot of times people ask me whether I'm mad and whether I would go back in the military. But it was Congress that passed the law, in 1993. The military has to follow the law of the land and the military is trying to enforce it. So I thought the best thing I could do is work towards getting rid of this law.

Do you think Americans are ready for a military that allows openly gay members?

Oh yeah. I believe they are. Times have changed since 1993. It's a new century, new thinking. We are fighting two wars and you can't afford to kick anyone out.

Pentagon general counsel Jeh Johnson and Gen. Carter Ham, who leads army forces in Europe, will serve as co-chairs of the yearlong study into how the ban can repealed without causing a major upheaval to the fighting forces.

Gates made the announcement in an appearance on Capitol Hill before the Senate armed services committee. It marks a measured step toward President Barack Obama's goal of eliminating the military's policy against gays.

Admiral Mike Mullen, chairman of the Joint Chiefs of Staff, also made an impassioned plea for allowing gays to serve openly in uniform, telling the Senate committee it is wrong to force people to "lie about who they are in order to defend their fellow citizens."

The law, passed in 1993 as part of the National Defence Authorization Act, says "homosexual conduct" is grounds for dismissal from the military. That includes "homosexual acts, or a homosexual marriage or attempted marriage," as well as any statements made that might indicate a propensity to engage in homosexual acts.

The regulations have affected an estimated 14,000 servicemen and servicewomen, including David Hall, a former sergeant in the U.S. air force who claims he was turfed after five years of service.

"It was very disappointing … to know that the only reason that I didn't get to become a pilot was just because of the fact that I was gay," Hall said. "It's the only federal law that allows the government … that specifically says the government's going to discriminate against a class of people."

In his State of the Union address on Jan. 27 Obama vowed to "work with Congress and [the] military to finally repeal the law that denies gay Americans the right to serve the country they love because of who they are.

"It's the right thing to do," Obama said, to great applause.

Policy 'has been effective'

But at Tuesday's committee hearing, it was clear not everybody agrees with him.

Sen. John McCain, the ranking Republican on the panel, publicly bristled at the Pentagon's decision to do the study, saying he is "deeply disappointed" and calling the assessment "clearly biased" because it presumes the law should be changed.

"Has this policy been ideal? No, it has not," McCain said. "But it has been effective."

Several other Republicans sided with McCain, warning Mullen and Gates not to pursue a change at a time when the United States is fighting two wars in Iraq and Afghanistan and facing a continuing threat of terrorism. Democrats said they would back a change in policy.

Senator Carl Levin, a Democrat from Michigan, and chairman of the committee, said a repeal of the law might be slipped into a broader military policy bill that authorizes defence spending.

Democratic Senator Mark Udall said his Colorado constituents pride themselves on allowing others to live and let live.

"You don't have to be straight to shoot straight," said Udall, quoting libertarian Barry Goldwater.

Gates suggested that lawmakers keep the intensity of debate in check until the military can get a better handle on how to proceed.